MRSA: discover route for vaccine

MRSA vaccine research has failed to produce a viable option for patients because of the inability to identify an agent that can break through the deadly bacteria’s unique armor. Most research has targeted the surface of the bacteria, but the URMC team have discovered an antibody that reaches beyond the microbe’s surface and can stop the MRSA bacteria from growing, at least in mice and in cell cultures.

The Orthopaedic Research Society invited URMC researchers to present their findings at the ORS annual meeting in Long Beach, Calif. The team is led by Edward M. Schwarz, Ph.D., professor of Orthopaedics and associate director of the URMC Center for Musculoskeletal Research. John Varrone, a second-year graduate student in Schwarz’s lab, will discuss the data at ORS and the ongoing search for attractive molecular candidates for use in a vaccine.

Staph infection is the leading cause of osteomyelitis, a serious bacterial infection of the bone. Up to half of these infections are due to MRSA, a particular strain of staph known as a “superbug” because of its antibiotic resistance. MRSA causes nearly 500,000 hospitalizations and 19,000 deaths a year in the United States. Although improvements in surgical techniques and use of prophylactic antibiotics prevents some MRSA infections, osteomyelitis is expected to remain a serious problem in the future as people live longer and request more joint replacements and reconstructive surgery.

Management of MRSA infections due to bone and joint surgery is very challenging, Schwarz said, and therefore a vaccine to prevent the infection is badly needed.

It is difficult to pin down the source of most post-surgical MRSA infections, but the health and financial consequences are severe. Hospital stays can last up to six months. Standard treatment includes removing the MRSA-colonized prosthetic joint replacement, then an extensive washing and draining of the infected area in an attempt to clear out all bacteria before it seeds in nearby tissue and bone. Antibiotic spacers are usually placed near the joint for six to eight weeks.

A second joint replacement is an option only if the antibiotic-spacer treatment is successful and the health of the patient remains stable. However, the re-infection rate is very high (40 to 50 percent) and remains a risk for months or even years after the initial assault. In some cases the patient never fully regains the use of the infected joint, said Regis O’Keefe, chief of Orthopaedics at URMC and an expert in the treatment of MRSA.

“It’s essential that we have mechanisms in place to prevent this awful infection,” O’Keefe said. “We are very excited about our vaccine research. It’ll have a phenomenal impact on individuals locally and across the country if we are successful.”